The difference between a traditional Advertising Agency and a Digital Marketing Agency is the "digital" part. Traditionally, advertisers focused on volume. Not only the volume of ads they publish, but also the volume of services offered.
The primacy/recency effect will cause a customer to continuously associate their first impression of your product or service, with what they're experiencing currently. In other words, if you traumatize them in the beginning, they're going to look for trauma in the future. If you make them feel incredible in the beginning, they're going to justify working with you when things get tough.
Getting on the first page of Google is not easy, but it's also not very hard. Your strategy should revolve around content and backlinks. If you publish enough content and have enough relevant & authoritative content linking back to your website, you WILL move up the ranks in Google search.